Ethylidene-bis-3 (nu-vinyl-2-pyrrolidone) and polymers thereof



United States Patent ETHYLIDENE-BIS-3(N-VINYL-Z-PYRROLIDONE) Thisinvention relates to a new divinyl monomer, more particularly toethylidene-bis-3(N-vinyl-2-pyrrolidone), to the process of preparing thesame, and to the process of copolymerizing it with other polymerizablevinyl monomers.

We have found that sodium can be dissolved in N-vinyl- Z-pyrrolidone ata temperature of from 120 to 130 C. with no evolution of hydrogen. Thissolution after cooling to room temperature solidifies to a waxymaterial. The latter, when hydrolyzed with water yields a white slurry,which after filtering, washing with water and drying, yields crudeethylidene-bis-3-(N-vinyl-Z-pyrrolidone), hereinafter referred to forsimplicity as EBVP, having a melting point of 117 C. During hydrolysislittle exotherm takes place with no evolution of hydrogen. Byrecrystallization from ethanol a pure material (crystalline Very similarto those of N viny1 2 pwr.o1idone, it was solid) having a melting pointof 121 C. is obtained.

Since we have not established the reaction mechanism, or identified theby-products, we do not know the stoichiometry of the reaction of sodiumwith N-vinyl-Z-pyrrolidone. The preferred range of sodium seems toencompass from 3 to 6% by weight of N-vinyl-2-pyrrolidone, correspondingto 0.15-0.30 atom of sodium per molecule of N-vinyl-Z-pyrrolidone. Theyield of EBVP in this range is about 30% elfective, based on the Weightof N- vinyl-2-pyrrolidone. Amounts of sodium higher than 6% are verydifiicult to dissolve, even over a long period, and the final productmay be a gummy oil rather than a This was agitated with volumes ofwater, partly dissolving and leaving a white slurry. After filtering,washing crystalline solid. Amounts of sodium lower than 3% give littleor no product, but a solution which upon standing develops an insolublepopcorn polymer.

As an alternative to the foregoing procedure, the sodium can bedissolved by refluxing a solution of N-vinyl-Z-pyrrolidone in aninert-solvent diluent such as toluene, heptane, etc. The amount of inertsolvent diluent employed is immaterial so long as there is sufficientN-vinyl-Z-pyrrolidone to satisfy the foregoing stoichiometricrequirement. We prefer, however, a solution of equal parts by weight.When the sodium is completely dissolved, the solution is cooled to roomtemperature and the inert-solvent diluent decanted from the waxymaterial. The waxy material is heated with the 'same weight ofinert-solvent diluent until sufficiently fluid to agitate, which aftercooling to room temperature is again decanted. The combined liquidextracts are then evaporated to dryness and the residue hydrolyzed witha five-fold weight of water. After washing and drying the hydrolyzedresidue, there is obtained EBVP in the same yield as before, but inslightly improved purity, i.e., melting at 119.4 C.

Instead of toluene or heptane as an inert-solvent diluent for theN-vinyl-Z-pyrrolidone there may be used such as, for example, xylene,cumene, kerosene, naphtha, octane, etc.

The following examples will serve to further illustnate our invention:

Example I A total of 25 grams of sodium metal was added over a half hourperiod to 475 grams of N-vinyl-Z-pyrrolidone and stirred at 120130 C.After about one more hour, the sodium had completely dissolved. Thesolution was allowed to cool and slowly solidified to a waxy material.

with water and drying in a vacuum oven, there was obtained 140 grams ofcrude EBVP, M.P. 117 C. By recrystallization from ethanol a purematerial, M.P. 121 C., was obtained.

Percent calculated for C H N O C, 67.71; H, 8.12;

N, 11.31. Percent found: C, 67.93; H, 8.04; N, 11.61.

The pure product has the following structure:

()JH: 1120 CHOH-CHOH2 Hit =0 0: Hz

N N E=GH2 H=CH2 The foregoing structure was established not only fromthe elementary analysis, which agrees very closely with the postulatedempirical formula, C H N O but also by means of nuclear magneticresonance which shows that the two-carbon moiety is an ethylidene grouplinking two N-vinyl-Z-pyrrolidone units in their 3-positions. Theunsaturation of the two vinyl groups was determined by iodination. Thevalue of 87.7% vinyl pyrrolidone corresponds to a molecular weight of253 for a compound containing two vinyls. Since infra-red andultra-violet spectra were sonably concluded that EBVP contained twoN-vinyl-Z- pyrrolidone units bound together with a two-carbon moiety,i.e. an ethylidene linkage.

Example II Twelve grams of sodium was dissolved in a refluxing solutionof 300 grams of vinyl pyrrolidone and 300 grams of toluene. When thesodium had completely dissolved. the solution was cooled and the toluenedecanted from the waxy precipitate. The precipitate was heated with 300grams more of toluene until it became fluid, which after cooling wasagain decanted.

The combined toluene extracts were evaporated to dryness and the residueagitated with a five-fold weight of water. After washing and drying,grams of EBVP, melting at 119.4", was obtained. By recrystallizationfrom ethanol, a pure material, M.P. 121 C. was obtained.

EBVP copolymers readily with N-vinyl lactams and other polymerizablemonomers containing a vinyl group to give products ranging fromthickened solutions to intractable gels depending upon the proportion ofEBVP used. EBVP is particularly usefiul for cross-linking variousN-vinyl-Z-pyrrolidone 5-methyl-N-vinyl-Z-pyrrolidone5-ethylN-vinyl-2pyrrolidone 3,3-dimethyl-N-vinyl-Z-pyrrolidone3-methyl-N-vinyl-2-pyrrolidone 3-ethyl-N-vinyl-2pyrrolidone4-methyl-N-vinyl-2-pyrrolidone 4-ethyl-N-vinyl-Z-pynrolidoneN-vinyl-Z-piperidone N-vinyl-e-caprolactam 3 The foregoing N-vin-yllactams are well known compounds and have been described in chemicalliterature as well as in United States Patents 2,265,450, 2,317,804 and2,335,454 in which working examples of most of the above using some ofthe water to transfer all the monomer to the flask. With a continuousnitrogen purge, the contents were heated to 55 C. with agitation. Basedon the weight of V.P., 2' /2% of 28% aqueous ammonia was species aregiven. 5 added, followed by the hydrogen peroxide catalyst. Sam- Thevarious monomers containingapolymerizable vinyl -ples were takenperiodically to determine the residual group, other than N-vinyllactams, which may be employed V.P. by iodination analysis. When theV.P. content was in polymerizations alone or in combination with each 7below 0.5%, the reaction was considered done. Further other or withN-vinyl lactams and cross-linked with EBVP, small additions of H may beadded at this point to include N-vinyl oxazolidone,N-vinylimidazolone,N-vinyldecrease the V.P. content further if deemednecessary. 3-morpholinone; vinyl acetate, vinyl methoxyacetate, vinylThe results obtained are as follows:

Run EBVP/V P 11202 P K-Value (A) Solids Comments on appear- No. ratioratio ance Percent Percent Percent 1 0.5 0 12 Softjelly-like material;does not rejoin when broken up. 2 0 0.25 12 Completely fluid. 3 0. 5 0.5 12 Soft jelly-like material. 4 0 0.5 12 Completely fluid. 1a--- 0.5.25 5 Viscous fluid. No

apparent gel. 2a 1.0 .25 5 Thin jelly-like material. Pours smoothly. 3a2.0 .25 5 Cloudy gel. Does not pour.

(A) The K-value is a function of the mean molecular weight as derived byH. Fikentscher, Cellulosechemie 13, 58 (1932).

diethylacetate, vinyl trimethylacetate, vinyl propionate, vinylisobntyrate, vinyl ibutyrate, vinyl acrylate, vinyl methacrylate, vinyllactate, vinyl caproate, vinyl caprylate, vinyl stearate, etc. Acrylicand methacrylic monomers such as methyl methacrylate, cyclohexylmethacrylate, isobutyl methacrylate, isoamyl methacrylate,B-methoxyethyl methacrylate and oc-(o-chlorophenyl) ethyl methacrylate,,8 phenoxyethyl methacrylate, ,3 phenylethyl methacrylate, phenylmethacrylate, o-cresol met-hacrylate, Pchlorohex-ylp henyl methacrylate,2-nitro-2- me-thylpropyl methacrylate, diethylaminoethyl methacrylate,ethylidene acetate methacrylate and glycidyl methacrylate, includingesters of haloacrylic acids, such as methyl-a-chloroacrylate, ethyl 0achloracrylate, phenyl-a-chloroacrylate, a-ethyl acrylic acid, methylacrylate, propyl acrylate, acrylic acid, methacrylic acid, etc.,acrylonitrile, acrylamide, methacrylamide, as well as N-alkyl and N-arylsubstituted acrylamides, monomers of vinyl alkyl and aryl esters, suchas methyl vinyl ether, ethyl vinyl ether, isopropyl vinyl ether, n-butylvinyl ether, isobutyl vinyl ether, 2-ethylheXy-1 vinyl ether, vinyl2-methoxyethyl ether, vinyl 2-chloroethyl ether, vinyl phenyl ether,oc-ChlOIOVinyl phenyl ether, otblO- movinyl phenyl ether, a-methylvinylphenyl ether, a-phenylvinyl phenyl ether, vinyl o-cresyl ether, vinylrn-cresyl ether, vinyl p-cresyl ether, a-methylvinyl p-cresyl ether,vinyl o-ethylphenyl ether, vinyl p-chlorophenyl ether, vinyl2,4-dichlorophenyl ether, vinyl 2,4,6-trichlorophenyl ether, vinylm-hydroxyphenyl ether, vinyl ot-naphthyl ether and vinyl fi-naphthylether, etc.

The following examples will serve to illustrate how polymerizations ofN-vinyl lactams, polymerizations of one or two monomeric vinylcompounds, other than N-vinyl lactams, and polymerizations of N-vinyllactam with any one of the foregoing polymerizable monomeric vinylcompounds, may be cross-linked with EBVP to yield polymers of increasedviscosity.

Example III Seven polymerization runs were made and compared with normalnuns of polyvinyl 2-pyrrolidone, the only difference being the inclusionor exclusion of the EBVP crosslinking agent. The runs were madeaccording to the :Eollowing polymerization technique dissolving EBVP inN-vinyl-2-pyrrolidone (V.P.) since EBVP is insoluble in water:

EBVP solution was first added to a reaction flask with reflux condenser,then the proper amount of water added,

Example I V Example V A solution of 100 grams of vinyl acetate in 222grams of isopropyl alcohol was heated at reflux for 4 hours with 1 gramof azoisobutyronitrile as catalyst. A polymer with a specific viscosity(1% solution in 90% isopropyl alcohol) of 0.05 was obtained. When EBVPwas substituted for 2% of the starting amount of vinyl acetate, aproduct of specific viscosity 0.10 was obtained.

Example VI Grams Vinyl pyrrolidone 140 Vinyl acetate 60 90% Ethanol 133Azoisobutyronitrile (AIBN) 0.4

The above solution was heated at reflux for 5 hours, 0.2 gram more AIBNwas added and it was held at reflux for 2 more hours. The product had aK-value of 42. The identical procedure with 1.0 gram of EBVP (present atthe start) gave a K-value of 55.

Example VII Grams Diethylene glycol monoethyl ether 250 Vinyloxazolidinone 188 Methyl methacrylate 62 Azoisobutyronitrile 0.38

The solution was stirred at 80 under nitrogen for 3 hours then heated toand held one hour. A viscous solution was obtained with a polymer ofK-value 42. The identical procedure with 7.5 grams of EBVP (present atthe start) gave a thick insoluble gel.

The cross-linked polymers prepared as above are especially useful in avariety of applications, depending on the degree of cross-linking. Thedegree of cross-linking is determined by the amount of EBVP used, andthe properties of the polymer change with the degree of cross-linking.Amounts of EBVP may range from 0.1% to 50% by weight and the balance ofeither a single polymerizable vinyl monomer or a mixture in anyproportions of two separate polymerizable vinyl monomers, in anyconventional polymerization reaction, to yield cross-linked polymers ofvarious characteristics.

Since EBVP is soluble in polar organic solvents, including N-vinyllactams and the aforementioned polymerizable monomers containing a vinylgroup, it is especially adaptable in the conventional solutionpolymerization technique.

Moderately cross-linked-polymers retain their solubility and are usefulas thickeners, protective colloids, and flocculants. More highlycross-linked polymers swell greatly but do not dissolve. They areparticularly useful to absorb various solutions. For example, a gelswollen with aqueous acid has proven useful in oil Well acidizing.

Still more highly cross-linked polymers become mechanically stronger andswell less. These are particularly useful as adsorbents and complexingagents for removing traces of materials such as tannins or phenols(which complex with polyvinyl pyrrolidone) from various solutions.

We claim:

1. Ethylidene-bis-3 (N-vinyl-Z-pyrrolidone) having the followingformula:

3. Polymers of polymerizable vinyl compounds copolymerized andcross-linked with 0.1% to 50% by weight of ethylidene-bis-3(N-vinyl-Z-pyrrolidone).

4. Polymers of N-vinyl lactams copolymerized and 6 cross-linked with0.1% to 50% by weight of ethylidenebis-3 (N-vinyl-2-pyrrolidone) 5.Polymers of N-vinyl-Z-pyrrolidone copolymerized and cross-linked with0.1% to 50% by weight of ethylidene-bis-S (N-vinyl-Z-pyrrolidone) 6.Copolymers of N-vinyl-Z-pyrrolidone and vinyl acetate copolymerized andcross-linked with 0.1% to 50% by Weight ofethylidene-bis-Ia'(N-vinyl-2-pyrrolidone).

7. The process of preparing cross-linked polymers which comprisescopolymerizing and .cross-linking from 99.9% to 50% by weight of atleast one polymerizable vinyl compound with 0.1% to 50% by Weight ofethylidene-bis-3 (N-vinyl-Z-pyrrolidone) in the liquid phase and in thepresence of a free radical catalyst.

8. The process of preparing cross-linked polymers which comprisescopolymerizing and cross-linking 99.9% to 50% by weight of a vinyllactam with 0.1% to 50% by weight ofethylidene-bis-3(N-vinyl-Z-pyrrolidone) in the liquid phase and in thepresence of a free radical catalyst.

9. The process of preparing cross-linked polymers which comprisescopolymerizing and cross-linking 99.9% to 50% by weight ofN-vinyl-Z-pyrrolidone with 0.1% to 5 0% by weight of ethylidene-bis-3(N-viny-l-Z-pyrrolidone) in the liquid phase and in the presence of afree radical catalyst.

10. The process of preparing cross-linked polymers which comprisescopolymerizing and cross-linking 99% by weight of methyl methacrylatewith 1% by weight of ethylidene-bis-3 (N-vinyl-Z-pyrrolidone) in theliquid phase and in the presence of a free radical catalyst.

11. The process of preparing cross-linked polymers which comprisescopolymerizing and cross-linking 98% by weight of vinyl acetate with 2%by weight of ethylidene-bis-3 (N-vinyl-Z-pyrrolidone) in the liquidphase and in the presence of a free radical catalyst.

12. The process of preparing cross-linked polymers which comprisespolymerizing and cross-linking 69.7% by weight of vinyl py-rrolidone and29.8% by weight of vinyl acetate with about .5% by weight ofethylidene-bis- 3(N-vinyl-2-pyrrolidone) in the liquid phase and in thepresence of a free radical catalyst.

13. The process of preparing cross-linked polymers which comprisespolymerizing and cross-linking 73% by weight of vinyl oxazolidone and24.1% by weight of methyl methacrylate with 2.9% by weight ofethylidenebis-3(N-vinyl-Z-pyrrolidone) in the liquid phase and in thepresence of a free radical catalyst.

No references cited.

JOSEPH L. SCHOFER, Primary Examiner.

H. WONG, Assistant Examiner.

1. ETHYLIDENE-BIS-3(N-VINYL-2-PYRROLIDONE) HAVING THE FOLLOWING FORMULA:3. POLYMERS OF POLYMERIZABLE VINYL COMPOUNDS COPOLYMERIZED ANDCROSS-LINKED WITH 0.1% TO 50% BY WEIGHT OFETHYLIDENE-BIS-3(N-VINYL-2-PYRROLIDONE).